This module adds an option `security.hideProcessInformation` that, when enabled, restricts access to process information such as command-line arguments to the process owner. The module adds a static group "proc" whose members are exempt from process information hiding. Ideally, this feature would be implemented by simply adding the appropriate mount options to `fileSystems."/proc".fsOptions`, but this was found to not work in vmtests. To ensure that process information hiding is enforced, we use a systemd service unit that remounts `/proc` after `systemd-remount-fs.service` has completed. To verify the correctness of the feature, simple tests were added to nixos/tests/misc: the test ensures that unprivileged users cannot see process information owned by another user, while members of "proc" CAN. Thanks to @abbradar for feedback and suggestions.
		
			
				
	
	
		
			131 lines
		
	
	
		
			4.4 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			131 lines
		
	
	
		
			4.4 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
# Miscellaneous small tests that don't warrant their own VM run.
 | 
						|
 | 
						|
import ./make-test.nix ({ pkgs, ...} : {
 | 
						|
  name = "misc";
 | 
						|
  meta = with pkgs.stdenv.lib.maintainers; {
 | 
						|
    maintainers = [ eelco chaoflow ];
 | 
						|
  };
 | 
						|
 | 
						|
  machine =
 | 
						|
    { config, lib, pkgs, ... }:
 | 
						|
    with lib;
 | 
						|
    { swapDevices = mkOverride 0
 | 
						|
        [ { device = "/root/swapfile"; size = 128; } ];
 | 
						|
      environment.variables.EDITOR = mkOverride 0 "emacs";
 | 
						|
      services.nixosManual.enable = mkOverride 0 true;
 | 
						|
      systemd.tmpfiles.rules = [ "d /tmp 1777 root root 10d" ];
 | 
						|
      fileSystems = mkVMOverride { "/tmp2" =
 | 
						|
        { fsType = "tmpfs";
 | 
						|
          options = [ "mode=1777" "noauto" ];
 | 
						|
        };
 | 
						|
      };
 | 
						|
      systemd.automounts = singleton
 | 
						|
        { wantedBy = [ "multi-user.target" ];
 | 
						|
          where = "/tmp2";
 | 
						|
        };
 | 
						|
      users.users.sybil = { isNormalUser = true; group = "wheel"; };
 | 
						|
      security.sudo = { enable = true; wheelNeedsPassword = false; };
 | 
						|
      security.hideProcessInformation = true;
 | 
						|
      users.users.alice = { isNormalUser = true; extraGroups = [ "proc" ]; };
 | 
						|
    };
 | 
						|
 | 
						|
  testScript =
 | 
						|
    ''
 | 
						|
      subtest "nixos-version", sub {
 | 
						|
          $machine->succeed("[ `nixos-version | wc -w` = 2 ]");
 | 
						|
      };
 | 
						|
 | 
						|
      subtest "nixos-rebuild", sub {
 | 
						|
          $machine->succeed("nixos-rebuild --help | grep SYNOPSIS");
 | 
						|
      };
 | 
						|
 | 
						|
      # Sanity check for uid/gid assignment.
 | 
						|
      subtest "users-groups", sub {
 | 
						|
          $machine->succeed("[ `id -u messagebus` = 4 ]");
 | 
						|
          $machine->succeed("[ `id -g messagebus` = 4 ]");
 | 
						|
          $machine->succeed("[ `getent group users` = 'users:x:100:' ]");
 | 
						|
      };
 | 
						|
 | 
						|
      # Regression test for GMP aborts on QEMU.
 | 
						|
      subtest "gmp", sub {
 | 
						|
          $machine->succeed("expr 1 + 2");
 | 
						|
      };
 | 
						|
 | 
						|
      # Test that the swap file got created.
 | 
						|
      subtest "swapfile", sub {
 | 
						|
          $machine->waitForUnit("root-swapfile.swap");
 | 
						|
          $machine->succeed("ls -l /root/swapfile | grep 134217728");
 | 
						|
      };
 | 
						|
 | 
						|
      # Test whether kernel.poweroff_cmd is set.
 | 
						|
      subtest "poweroff_cmd", sub {
 | 
						|
          $machine->succeed("[ -x \"\$(cat /proc/sys/kernel/poweroff_cmd)\" ]")
 | 
						|
      };
 | 
						|
 | 
						|
      # Test whether the blkio controller is properly enabled.
 | 
						|
      subtest "blkio-cgroup", sub {
 | 
						|
          $machine->succeed("[ -n \"\$(cat /sys/fs/cgroup/blkio/blkio.sectors)\" ]")
 | 
						|
      };
 | 
						|
 | 
						|
      # Test whether we have a reboot record in wtmp.
 | 
						|
      subtest "reboot-wtmp", sub {
 | 
						|
          $machine->succeed("last | grep reboot >&2");
 | 
						|
      };
 | 
						|
 | 
						|
      # Test whether we can override environment variables.
 | 
						|
      subtest "override-env-var", sub {
 | 
						|
          $machine->succeed('[ "$EDITOR" = emacs ]');
 | 
						|
      };
 | 
						|
 | 
						|
      # Test whether hostname (and by extension nss_myhostname) works.
 | 
						|
      subtest "hostname", sub {
 | 
						|
          $machine->succeed('[ "`hostname`" = machine ]');
 | 
						|
          #$machine->succeed('[ "`hostname -s`" = machine ]');
 | 
						|
      };
 | 
						|
 | 
						|
      # Test whether systemd-udevd automatically loads modules for our hardware.
 | 
						|
      $machine->succeed("systemctl start systemd-udev-settle.service");
 | 
						|
      subtest "udev-auto-load", sub {
 | 
						|
          $machine->waitForUnit('systemd-udev-settle.service');
 | 
						|
          $machine->succeed('lsmod | grep psmouse');
 | 
						|
      };
 | 
						|
 | 
						|
      # Test whether systemd-tmpfiles-clean works.
 | 
						|
      subtest "tmpfiles", sub {
 | 
						|
          $machine->succeed('touch /tmp/foo');
 | 
						|
          $machine->succeed('systemctl start systemd-tmpfiles-clean');
 | 
						|
          $machine->succeed('[ -e /tmp/foo ]');
 | 
						|
          $machine->succeed('date -s "@$(($(date +%s) + 1000000))"'); # move into the future
 | 
						|
          $machine->succeed('systemctl start systemd-tmpfiles-clean');
 | 
						|
          $machine->fail('[ -e /tmp/foo ]');
 | 
						|
      };
 | 
						|
 | 
						|
      # Test whether automounting works.
 | 
						|
      subtest "automount", sub {
 | 
						|
          $machine->fail("grep '/tmp2 tmpfs' /proc/mounts");
 | 
						|
          $machine->succeed("touch /tmp2/x");
 | 
						|
          $machine->succeed("grep '/tmp2 tmpfs' /proc/mounts");
 | 
						|
      };
 | 
						|
 | 
						|
      subtest "shell-vars", sub {
 | 
						|
          $machine->succeed('[ -n "$NIX_PATH" ]');
 | 
						|
      };
 | 
						|
 | 
						|
      subtest "nix-db", sub {
 | 
						|
          $machine->succeed("nix-store -qR /run/current-system | grep nixos-");
 | 
						|
      };
 | 
						|
 | 
						|
      # Test sudo
 | 
						|
      subtest "sudo", sub {
 | 
						|
          $machine->succeed("su - sybil -c 'sudo true'");
 | 
						|
      };
 | 
						|
 | 
						|
      # Test hidepid
 | 
						|
      subtest "hidepid", sub {
 | 
						|
          $machine->succeed("grep -Fq hidepid=2 /etc/mtab");
 | 
						|
          $machine->succeed("[ `su - sybil -c 'pgrep -c -u root'` = 0 ]");
 | 
						|
          $machine->succeed("[ `su - alice -c 'pgrep -c -u root'` != 0 ]");
 | 
						|
      };
 | 
						|
    '';
 | 
						|
})
 |